EP1221637B1 - Escapement for timekeeper - Google Patents

Abstract

The escapement includes first (3) and second (4) escapement wheels meshing with each other, one of these wheels being driven by the gear train. It further includes a lever (5) capable of receiving the impulses generated alternately by the first and second wheels and to transmit these impulses to a plate (2) which carries a sprung-balance. The lever is arranged to lock alternately the first and second wheels after each impulse transmitted.

Description

The present invention relates to an escapement disposed between a gear train and a platform to which a pendulum of a timepiece is attached, the balance being able to traverse a free oscillation arc and to receive oscillation maintenance pulses. This escapement comprises first and second wheels, rotating according to respective first and second axes of rotation, each comprising a toothing and meshing with each other by the toothing, one of these wheels being intended to be driven by the train. The exhaust further comprises a rocker arranged to alternately block the first and second wheels after each maintenance pulse pendulum oscillations.

The applicant of the present invention has already proposed an escape partially answering the definition which has just been given and a description of which is explained in the document EP-A-1 041 459 . This document describes an escapement comprising first and second wheels meshing with each other. One of these wheels is driven by the gear train. First and second plates integral with a common shaft support a balance-spiral. The wheels and the first plate are provided with means allowing said first plate to receive direct pulses delivered alternately by the first and second wheels in order to maintain oscillations of the balance. The second plate is provided with means for driving a locking rocker arranged to alternately block said first and second wheels.

The present invention thus takes up an essential character of what is described in the cited document, namely two wheels meshing with each other, one of these wheels being driven by the gear train. However the idea developed in the quote to use two superimposed trays, one used to receive direct pulses alternately conferred by the first and second wheels and the other used to block alternately, via a rocker, said first and second wheels have been abandoned in the present invention for obvious reasons of simplification of the mechanism.

As will be seen from the description which follows, a single plate supporting the sprung balance cooperates with a rocker which cooperates in turn and alternately with the first and second wheels.

It will thus be understood that the rocker performs a dual function: firstly to transmit to the plate the pulses received alternately first and second wheels and then to alternately block said wheels after each pulse.

Such a mechanism is described in the document DE 24 58 503 A . However, unlike the escapement present here it is provided that the rocker according to the present invention comprises a first and a second housing, for alternately receiving the pulses, each of which is arranged to cooperate with the same toothing of one of the two wheels that the one by which the latter are in mutual engagement. Thus, a second, specific toothing is not necessary.

It will therefore be understood that the entire exhaust mechanism is confined in a single plane and thus the overall height of this mechanism is halved compared to the footprint occupied by the exhaust of the documents cited.

The exhaust according to the invention is defined by claim 1.

• les figures 1 à 6 sont des vues en plan de l'échappement selon l'invention représenté en six stades différents décrivant une oscillation complète du balancier,
• la figure 7 est un agrandissement de la zone VII montrée en figure 2, et
• la figure 8 est un agrandissement de la zone VIII montrée en figure 3.

The invention will now be explained in detail below by an exemplary embodiment, this embodiment being illustrated by the appended drawings in which:

• the Figures 1 to 6 are plan views of the exhaust according to the invention shown in six different stages describing a complete oscillation of the balance,
• the figure 7 is an enlargement of Zone VII shown in figure 2 , and
• the figure 8 is an enlargement of zone VIII shown in figure 3 .

The Figures 1 to 6 are plan views of six successive phases of the escapement according to the invention, these phases covering a complete oscillation of the sprung balance. The escapement 1 is arranged, as is usual, between a cog and a plate 2 supporting a balance-spring of a timepiece. The balance-spring, not shown in the figures, is able, as is known, to go through a free oscillation arc and arranged to receive maintenance pulses of these oscillations. By definition, the wheel, also called finishing, is the set of wheels and gears which, a barrel, transmits the driving force to an escape wheel. In figure 1 , the gear is represented by its last wheel 30, associated with the pinion 31. The wheel 30 drives a first wheel 3 exhaust by the pinion 32 which is secured thereto. The first wheel 3 meshes with a second wheel 4. The wheels 3 and 4 have the same diameter and the same number of teeth. It will be noted here that the finishing wheel 30 could drive the second escape wheel 4 in place of the first wheel 3.

What has just been said is known from the document EP-A-1 041 459 which already shows an escapement with two wheels meshing with each other and arranged for transmitting direct pulses to a first plate while a second plate causes a latch blocking in turn the first then the second escape wheel.

Compared to this prior arrangement, the present invention is remarkable in that it comprises a rocker 5 adapted to receive pulses generated alternately by the first and second escape wheels 3 and 4 as shown in the figures accompanying this description. In a very general manner, these figures make it obvious that the latch 5, in turn, transmits the pulses received to the plate 2 to drive it in rotation so as to maintain the oscillations of the balance-spiral integral with the plate 2 The same figures also make it apparent that the rocker is arranged to alternately block the first and second escape wheels 3 and 4, after each pulse has been transmitted to the plate 2.

We will now discuss in more detail a preferred embodiment of the invention that allows to implement the principle of escape defined in the paragraph above.

As shown in the figures, the rocker 5 equipping the exhaust according to the invention is supported by a shaft 6 pivoting freely in a plate (not shown) that includes the timepiece. This rocker 5 has a substantially triangular shape.

A first vertex of the rocker comprises a first housing 7 into which the end of a tooth 8 of the first wheel 3 can be introduced to subject the rocker 5 to a pulse in a first direction A. This introductory situation is not represented in the drawing, but it will be understood that it follows the phase presented in figure 6 .

A second top of the rocker comprises a second housing 9 in which can be introduced the end of a tooth 10 of the second wheel 4 to subject the rocker 5 to a pulse in a second direction B, inverse to the first direction A. This situation is shown in the drawing at figure 2 as well as figure 7 which is an enlargement of zone VII of the figure 2 .

Finally, a third vertex of the rocker 5 comprises two teeth 11 and 12 capable of meshing with a single tooth 13 that the plate 2 comprises, a situation of total meshing being well apparent to the figures 2 and 7 .

It will now be explained how the teeth of the two wheels cooperate with the rocker 5 to subject said flip-flop to pulses and to block the same flip-flop after each pulse transmitted.

It will be noted first of all, with reference to figures 7 and 8 , that the first and second housings 7 and 9 of the rocker 5 are connected by an edge 14 having a circular configuration whose radius of curvature R1 passes through the axis 15 of the shaft 6 which supports the rocker 5. It will also be observed that the teeth of the first and second wheels 3 and 4 each have a front flank 16 defined as facing the respective advance direction of each of the wheels. Each front flank 16 comprises a first curved top cutout 17, called the locking face, whose radius of curvature R2 is substantially the same as the radius of curvature R1 of the edge 14 connecting the first and second housings 7 and 9 of the flip-flop 5. As the figure 8 this blocking face 17 comes to bear against the edge 14 of the rocker 5 to block one of the wheels 3 and 4, in this case the wheel 3. A similar situation, blocking the wheel 4, is shown in FIG. figure 1 . Each front flank 16 also has a second cutout 18, in an arc of a circle, called the impulse face, this second cutout 18 following the first cutout 17. As can be seen from FIG. figure 7 this pulse face 18 comes to bear against an edge 19 defined as being the intersection of the edge 14 of the rocker 5 and one of the housings 7 and 9 of the same rocker, in this case the housing 9 This support causes the rocker 5 to rotate in the direction of the arrow B and, consequently, drives the plate 2 in the direction of the arrow E. The pulse is thus given to the sprung balance.

Since it is important to avoid a reversal (due for example to a shock) of the rocker 5 during the course of the free oscillation arc of the balance and therefore of the plate 2 to which it is attached, it will size each of the two teeth 11 and 12 occupying the third top of the rocker 5 to adjoin the edge 20 of the plateau 2. Such situations are shown on the figures 4 and 5 .

Finally it will be understood that it is important to limit the angular excursion of the rocker 5. This limitation can be made in two different executions.

A first embodiment consists in providing the first and second peaks of the rocker 5 with first and second horns 21 and 22, respectively, as shown in all the figures and particularly in FIG. figure 8 . The first horn 21 abuts against the rear flank 23 of a tooth 24 of the first wheel 3 as shown in FIG. figure 1 . Similarly, the second horn 22 abuts against the rear flank of a tooth 10 of the second wheel 4 as seen on the figures 3 and 8 . Note here that the rear flank 23 of the teeth in question is defined as turning the back to the respective forward direction of each of the wheels.

A second execution is to limit the excursions of the rocker 5 by means of two pins 25 and 26 stuck in the plate of the timepiece as this is shown in dotted lines on the figure 8 . It will be understood that the horns 21 and 22 equipping the rocker 5 are no longer necessary and can be removed. At this time the first and second peaks of the rocker 5 could end in the dotted line 35, respectively 36 which could be an extension of the arcuate edge 14 connecting the housing 7 and 9.

A preferred embodiment of the new exhaust having been described above as well as the functions performed by the various parts composing them, we will now review its actual operating mode by describing a complete cycle. We will examine in turn the Figures 1 to 6 which show six important phases of this cycle.

First phase (Figure 1)

The mechanism is stopped. The second escape wheel 4 is blocked because the locking face of its tooth 10 rests on the edge 14 connecting the housings 7 and 9 of the rocker 5. The angular excursion of the rocker 5 is exhausted since its horn 21 rests on the rear flank 23 of the tooth 24 of the first escape wheel 3. At this moment the balance spring is close to the end of oscillation (arrow E) or near the end of second alternation of this oscillation . The tooth 13 of the plate 2 comes into contact with the tooth 12 of the rocker 5 and will cause said rocker in the direction of the arrow B. It is a phase of disengagement of the rocker where on the one hand the horn 21 and the edge 14 can slide on the rear flank 23 of the tooth 24 and on the other hand the edge 14 can be erased in front of the locking face of the tooth 10.

Second phase (Figures 2 and 7)

The latch 5 continues its course in the direction of the arrow B, driven that it is by the plate 2. At this moment the tooth 13 of the plate is fully engaged between the two teeth 11 and 12 of the rocker. The tooth 10 of the second escape wheel has penetrated into the housing 9 of the rocker and the impulse face 18 of the tooth 10 comes into contact with the edge 19 of the rocker. The escape wheel 4 is then driven in the direction of the arrow F by means of the escape wheel 3 which rotates in the direction of the arrow G driven that it is in turn by the wheel whose last element 30 was shown in figure 1 . It is a pulse phase that starts the tray in the direction of the arrow E and turns the rocker in the direction of the arrow B until this rocker meets the blocking face of a tooth of the first escape wheel.

Third phase (Figure 3 and 8)

When the tooth 13 of the plate 2 leaves the tooth 11 of the rocker, the locking face 17 of the tooth 8 of the first escape wheel 3 abuts against the edge 14 of the rocker thus blocking the first and second wheels 3 and 4 From this moment the plate 2 starts a second oscillation in the direction of the arrow E. The rocker is then retained either by the horn 22 which bears against the rear edge 23 of the tooth 10, or by the pin 25 according to the limiting solution we chose.

Fourth phase (Figure 4)

The situation of the rocker is the same as that described above with the difference that its tooth 11 adjoins the edge 20 of the plate 2 to prevent overturning. The plateau continues to rotate in the direction of the arrow E and travels the first half of its second free oscillation. The rocker 5 and the first and second wheels 3 and 4 are still blocked.

Fifth phase (Figure 5)

After having traversed its first alternation, the plateau returns in the opposite direction shown by the arrow M and travels the second alternation of its second free oscillation. The rocker 5 always blocks the first and second wheels and is always prevented from overturning by the action of its tooth 11 against the edge 20 of the plate 2.

Sixth phase (Figure 6)

The tooth 13 of the plate 2 comes into contact with the tooth 11 of the rocker 5 which will cause the latter in the direction of the arrow A. Here we find ourselves in a situation similar to that illustrated by the figure 1 , that is to say at the beginning of a new release phase which will allow the tooth 8 of the first wheel 3 to be introduced into the housing 7 of the rocker 5 to restart the plate 2. A from this sixth phase a new cycle starts again similar to that just described, the blocking then acting on the second escape wheel 4.

Final considerations

It has already been indicated above that the escapement according to the invention takes up very little height space since all the parts involved (escape wheels, rocker, plate) are at the same level on a single plane. It is also noted that this system involves fewer parts than those used in the escapement described in connection with the document cited above. EP-A-1 041 459 , thus making it possible to propose a less expensive mechanism. In addition the parts involved are very simple which ensures overall a great security of operation.

We have seen that the impulse on the rocker 5 is given by a tooth 10 of one of the escape wheels 4 on a ridge 19 made on the rocker 5 (see figure 7 ). The tooth portion that gives this pulse is the second cutout 18 which has a shape in an arc. This recalls the relaxation escapement known from the state of the art and used mainly in chronometry. This way of doing things is very economical in terms of energy expended since the contact of the parts in the presence is reduced to an edge rubbing on an arc of a circle. Note however, that unlike the escapement trigger, the exhaust according to the invention is self-starting.

It will also be noted that the pulse is communicated to the plate 2 by an intermediate piece, here called flip-flop 5. This is reminiscent of the Swiss lever escapement where the pulse is transmitted to the plate by a fork. Anchor escapement however has a disadvantage, namely the retreat of the escape wheel at the time of release, this recoil has the disadvantage of braking the balance and therefore consume energy. In the escapement of the present invention there is no recoil since the radius of curvature R1 of the edge 14 of the rocker 5 is the same as the radius of curvature R2 of the first cutout 17 of the tooth 8 of the wheel 3 (see figure 7 and 8 ).

It should be noted that the proposed system does not need to be lubricated. This is due to the contact surfaces reduced to a minimum both as regards the region where the pulse is given (edge 19 and cutout 18) that the region concerned by the clearance (very small cutout 17).

Claims (6)

1. Escapement (1) intended to be arranged between a gear train and a plate (2) to which is attached a spring balance of a timekeeper, the balance being able to travel through a free arc of oscillation and receive impulses for maintaining the oscillations, this escapement including
   first (3) and second (4) wheels, rotating according to first and second rotating axes respectively, each wheel comprising a toothing and meshing with each other, one of these wheels being intended to bedriven by the gear train,
   a lever (5) able to receive impulses generated alternately by the first (3) and second (4) wheels and to transmit these impulses to said plate (2) to drive it in rotation and to maintain the balance oscillations, said lever (5) being arranged to lock alternately said first (3) and second (4) wheels after each impulse transmitted,
   characterised in that said lever comprises a first and a second recesses (7, 9) to alternatively receive dais impulses, each of said recesses being arranged to cooperate with said toothing of one of said first and second wheels, and so that said impulses are oriented toward the mediating plane of a segment linking said first and second rotating axes of said wheels and being perpendicular to them.
2. Escapement according to claim 1, characterised in that the lever (5) is intended to be supported by a shaft (6) freely pivoting in a plate of the timekeeper and in that t his lever (5) has a substantially triangular shape a first top of which includes said first recess (7) in which the end of a tooth (8) of the first wheel (3) can be introduced to subject the lever (5) to an impulse in a first direction (A), a second top of which includes said second recess (9) in which the end of a tooth (10) of the second wheel (4) can be introduced so as to subject the lever (5) to an impulse in a second direction (B), opposite to the first direction, and a third top of which includes two teeth (11 and 12) capable of meshing with a single tooth (13) of the plate (2).
3. Escapement according to claim 1 or 2, characterised in that the first (7) and second (9) recesses of the lever (5) are connected by an edge (14) having a circular configuration whose radius of curvature (R1) passes through the axis (15) of the shaft (6) supporting the lever (5) and in that each of the teeth (8, 10) of the first (3) and second (4) wheels has a working flank (16) including a first curved top cut out portion (17), called the locking face, whose radius of curvature (R2) is substantially the same as that of the radius of curvature (R1) of the edge (14) connecting the first (7) and second (9) recesses of the lever (5), said locking face (17) being capable of abutting against said edge (14) of the lever to lock one (3) of said wheels, and a second cut out portion (18) in the shape of an arc of a circle, called the impulse face, following the first cut out portion (17), said impulse face (18) being capable of abutting against an edge (19) defined by the intersection of said edge (14) of the lever and one (9) of said recesses to drive the lever in rotation.
4. Escapement according to claim 2, characterised in that each of the two teeth (11 and 12) occupying the third top of the lever (5) is dimensioned so as to be contiguous with the edge (20) of the plate (2) and thus to prevent the lever from overbanking during the balance's free oscillation arc travel.
5. Escapement according to claim 2, characterised in that the angular travel of the lever (5) is limited by first (21) and second (22) horns located respectively at the first and second tops of said lever, the first horn (21) being capable of abutting against the non-working flank (23) of a tooth (24) of the first wheel (3) and the second horn (22) being capable of abutting against the non-working flank (23) of a tooth (10) of the second wheel (4).
6. Escapement according to claim 1 or 2, characterised in that the angular travel of the lever (5) is limited by two pins (25, 26) driven into the time-keeper plate.

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